Hassan’s legacy and expertise trace back to some of Silicon Valley’s most storied companies and technologies. Sometimes known as the unofficial third founder of Google, Hassan programmed much of the Google search engine. Hassan also was a key architect and software developer for Alexa Internet and Stanford Digital Library. Hassan also founded eGroups, which was bought by Yahoo. When Mr. Page and Mr. Brin founded Google in 1998, Mr. Hassan bought 160,000 shares for $800. When Google went public in 2004, the shares were worth more than $200 million. The shares, now in Google’s parent company, Alphabet, would be valued at more than $13 billion today. While Mr. Hassan never worked for Google, he was one of the founders of a company called eGroups, which was sold to Yahoo in 2000 for $432 million in stock. He also started two robotics firms. Hassan became passionate about robotics and founded Suitable Technologies in 2011. The firm went bankrupt in 2019. In 2006, Mr. Hassan formed a limited liability company called Greenheart Investments. In a pretrial filing, lawyers for Ms. Huynh said Greenheart had invested in more than 15 technology businesses and more than 30 real estate properties, including a 195-unit apartment complex in Menlo Park, less than a mile from Facebook’s offices. Greenheart was valued at more than $1 billion in 2015, the filing said. Ms. Huynh said Mr. Hassan owns more than 50 limited liability companies to hold his tech investments and real estate properties. Mr. Hassan said there were more like 20 for his real estate holdings as well as two “umbrella” L.L.C.s for his other investments.